ELECTRICAL INTERFERENCE

Radio Record, Volume I, Issue 43, 11 May 1928, Page 3

ELECTRICAL INTERFERENCE

X-RAY, VIOLET-RAY, MOTORS, ETC Broadcasting is being taken seriously in America. ‘The latest evidence of this is the action taken by many of the municipal authorities in the United States of America to prevent interfer ence .with programmes by induction noises from electrical machinery, One town has just gone so far as to pra« hibit the use of electrical machinery likely to cause interference with wire less reception between 8 v’clock and 10 o’clock at night. ‘The order has beet made very comprehensive, and it pro« vides, among other things, that hos« pitals must not use their X-ray plants between these hours except in cases of emergency. Although listeners do not always reae lise it, electrical machinery causes 4 great deal of interference with broade cast reception A simple proof of this can be obtained by turning on the electric light in a room in which a receiver is operating. As the switch is closed a loud click will almost in variably be heard in the loudspeaker. Various Causes. Electric motors, such as those used t> drive electric fans, are great offend. ets, and produce a continuous noise in the speaker. This noise is seldom troublesome if one is s«eeiving loud local stations, but it will often prevent long-distance reception Violet-ray machines cause even more intense ine terference, and one of the worst offend. ers of all is the battery charger used by amateurs themselves. For this reas son battery chargers, particularly those of the vibrating reed type, should be vsed as little as possible in broadcast« ing hours. ‘There are other sources of clectrical interference which can seldom be controlled. These are vari« ous forms of defects, usually teaks which develop in the insulating mater ial, on the reticulatiuu service itself, The only effective means of overcoms ing this interference appears to be to provide broadcasting stations ‘so powers ful that fey wil! entirely drown the interference. This is quite possible over short distances, but impossible over long distances, and it seems that, for the time being at any rate, listeners must suffer a certain amount of inter ference from clectrical services.